Press for drawing sheet metal



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'C. J. RHODES PRESS FOR DRAW INC SHEET METAL Filed Nov. 12, 1949 Oct.28, 1952 Patented Oct. 28,

UNITED STATES PATENT. OFFICE Application November 12, 1949, Serial No;126,755 7 4 In Great Britain August 5, 1949 1 Claim. 1

This invention relates to improvements in or relating to presses fordrawing sheet metal, and more particularly to a press of the kind inwhich an upper die carried by a ram co-operates with a lower diesupported on the bed-plate of the press, and in which the lower die isprovided with a forming block and with a draw ring supported by apressure plate beneath the bed of the press, the pressure plate beingoperatively connected to the forming block so as'to raise the formingblock against the'action of a return spring as the draw ring andpressure, plate are the accompanying drawing, the single figure ofdepressed by the descending upper die during,

the drawing operation.

In known presses of this kind the work is stripped from the formingblock solely by the effort exerted by the return spring, which reassertsitself and returns the pressureplate and draw rings upwards and theforming block downwards to their original positions, as the upper dieascends on the return stroke of the ram. When, however, the dies have toiron the metal as well as. to draw it, as in the production of aluminumstampings, the stripping effort required may be greater than the effortof which thereturn spring is capable.

It is an object of the invention to provide a sheet metal drawing pressin which the work is positively stripped from the forming block.

It is a further object of the invention to provide a sheet metal drawingpress suitable for drawing aluminum.

According to the invention there is provided an improved press fordrawing sheet metal .in which an upper die carried by a ram co-operateswith a lower die supported on the bed-plate of the press, and in whichthe lower die is provided with a forming block and with a draw ringsupported by a pressure plate beneath the bed of the press, the pressureplate being operatively connected to the forming block so as to raisethe forming block against the action of a return spring as the draw ringand pressure plate are which shows:

A part-sectional front elevation of a press according to the invention.

Referring to the drawing, inwhich only such parts of the press are shownas are necessary for *the proper understanding of the invention, iindiengage an appropriate thread formed in a hole depressed by thedescending upper die during the drawing operation, including a linkageby means of which the ram is operatively connected to the pressure plateduring the early part of the rethe pressure plate an upward motion whichraises the draw ring and depressesthe forming block, whereby the work ispositively stripped from the forming block by motion derived from theram.

Preferably the linkage comprises a pair or depending links pivotallyattached to the ram and cam means are provided for swinging the linksturn stroke of the ram only, so as to impart toin the block 3. The drawring 3a is supported by pins 31) resting on the ring 4. Secured to thebed-plate, I by means of nuts 6 countersunk into the upper surface ofthe said bed-plate are each of which is reduced indiameter where itenters the said bed-plate and is screw-threaded to engage one of thenuts 6. The rods 1, of which four are provided, form guides for apressure plate 8, the rods serving to prevent the plate from tilting orrocking as it moves upwards and downwards.

The rods 1 are each reduced in diameter at their lower ends and eachscrew-threaded for the reception of a nut 10 whereby there is secured tothe said rods a bracket having vertical side cheeks H and 12 in each ofwhich holes are formed for the passage or" the lower ends of the saidrods. The side cheeks II and !2 are suitably spaced apart to accommodatea pair of lower rollers 13 mounted on spindles M and a pair of pinionsl6 mounted on spindles I5, the spindles I4 and it being supported ateach end thereof by the cheeks and I2. A pair of upper rollers 26 freelymounted on spindles 21 are also accommodated between the upper portionsof the cheeks I I and I2, the spindlesthereof being supported by "thesaid cheeks.

The rod 5 has, intermediate its ends, an enlarged portion I! having uponopposite sides 3 provided upon their inner faces with teeth indicated byI9 forming racks which engage with the pinions 16, the engagement of theracks with the pinions being ensured by the rollers I3 which engage theouter surface of the members IS. The members l8 are also provided ontheir outer surface near the upper ends thereof with inclined orbevelled ledges Isa.

The rod has a reduced lower portion 20 which is screw-threaded part-wayalong its length from the lower end thereofand provided with locknuts 2|and 22, the nut 22 supporting a bushing 23 against the collar of whichabuts the lower end of a helical spring 24 encircling the'said-reducedportion 20 and having its upper end bearing against a horizontaltransverse plate 25 extending between the cheeks l l and I2 of theaforesaid bracket.

The upper die 28 of thepress is carried by the ram 29. A pair ofdepending links 30 pivotally attached to the ram extend'downwardly intothe vicinity of the upper portions of the rack members. The links 30 areeach provided on the inner side near the lower end thereof with aninclined or bevelled ledge 32 and are provided on the outer surface witha ramp 33 on to which the rollers 26 run immediately after the upper die28 contacts the metal blank.

The effective length of the links 30 isadjustable by means ofturnbuckles 3| so that when the upper die 28 carried by the ram 29contacts the metal blank resting on the lower die 2, the ledges 32 ofthe links 30 are at a level slightly below that of the ledges l9a on therack members l8.

The positivestripping device functions as follows:

As the upper die 28 moves downwards on to the metal blank its pressureis transmitted through the draw ring 3a and pins 31) to the collar orring 4 and so to the pressure plate 8 causing the latter to bedepressed. The depression of the pressure plate 8 causes the rackmembers l8 to rotate the pinions I5 which, owing to their engagementwith the teeth lla upon the enlarged portion H on the rod 5 cause theforming block 3 to be raised, compressing the return spring 24. As theram 29 approaches the bottom of its stroke the links 30 are caused toswing inwards by the ramps 33 00- operating with the rollers 26,bringing the ledges 32 into their operative position in which theyengage beneath the corresponding ledges Illa on the rack members [8.

Upon the upward movement of the ram, the ledges 32 engage the ledgesIlla whereby a positive upward motion is imparted to the pressure plate8 and draw ring 3a whilst a positive downward movement is imparted to,the forming block 3 through the rack members I8 engaging with thepinions l'B which-in turn engagethe teeth Ila on the enlarged portion llof the rod 5.

By virtue of the above arrangement, the Work is positively stripped fromthe forming block 3 4 during the early part of the return stroke of theram. Since the ledges 32 and I 9a are bevelled, they slip out ofengagement, and the links 30 swing outwards again to their normalpositions when the rollers 26 leave the ramp 33 just before the pressureplate 8 has returned to its normal position. The return of the pressureplate 8, draw ring 311 and forming block 3 to theirnormal positionsisassisted and completed by the spring 24 reasserting itself.

What I claim is:

A press for drawing sheet metal, comprising a bed-plate, a lower diesupported on said bedplate, a rammovable with an up and down stroke awayfrom and towards said lower die, an upper diecarried by said ram andco-operating with said lower die, a draw ring movable up and down withinsaid lower die and arranged to be depressed by said upper die during thedown stroke of said ram, a pressure'plate movable with and supportingsaid draw ring, a rod movable axially up and down with respect to saidbed-plate, a forming block carried by the upper end of said rodandmovable Within saiddraw ring,.tw o racks formed .on opposite sides ofsaid rod/two corresponding rack members depending from said pressureplate, two pinions supported from said bed-plate, each pinion engagingbetween a rack on said rod and the corresponding rack member dependingfrom said pressure plate, a return spring arranged to be stressed byupward movement of saidrod, a ledge on the outer side of each rackmemberfa link depending from each side of the ram and swingable inwardsinto engagement with the corresponding depending rack member, a ledge onthe inner side of each link and engageable beneath the correspondingledge of thecorresponding rack member, onswinging the link inwards asaforesaid, said ledges on said links and rack member being bevelled soas to cam said links out of engagement with said rack members, ramps onthe outer sides of said links, and rollers supported from said bed-plateand co-operating with said ramps to swingsaid links into engagementwith, said rack members at a predetermined point of the down stroke ofsaid ram and to allow said links to be cammed out of engagement at thesame point on the up of said ram.

. CHARLES JOSEPH RHODES- REFERENCES CITED The following referencesareof-irecord in the file of this patent: V

U I ED STATES PATENTS- stroke, 7

